The separation of azeotropic mixtures is of particular importance for bio-based processes in the chemical industry. Extractive and heteroazeotropic distillation are oftentimes the favored solution for medium to large scale processes due to their proven robustness and the economics of scale. The feasibility as well as economic efficiency of these processes depends strongly on the selection of a suitable mass separating agent (MSA). Furthermore, energy integration can increase the energy and economic efficiency of these thermal processes. Since, MSA selection, process design and energy integration are usually performed as consecutive steps in process design, potential synergies are easily missed, resulting in sub-optimal choices. In order to determine an optimal process design, including solvent selection and energy integration, an efficient optimization-based approach for the design of extractive distillation processes is proposed. The application of the method is illustrated for the separation of the azeotropic mixture of acetone and methanol. The results highlight that the optimal MSA choice under consideration of energy integration differs from the selection without energy integration.